Patent GB-647962-A (GB)
Title: Magnetic recording and reproducing apparatus
IPC: G11B15/16
Filed: 1947-08-18
Abstract: 647,962. Magnetic sound recording and reproducing apparatus. BRUSH DEVELOPMENT CO. Aug. 18, 1947, No. 22875. Convention date, Aug. 16, 1946. [Class 40 (ii)] [Also in Group XVI] In a recording and reproducing apparatus for magnetic tape, provision is made for both slow and fast forward and rewinding operations, the tape 31 in the slow (normal) forward operation being drawn by a capstan 37 over the erasing and transducer heads 41, 42, respectively, against which the tape is held by pads 81 on levers 82 operated by the " Forward " switch 72. The tape also passes over a limit-switch member 38 by which means the circuits of the forward motors 51, 69 are maintained through contacts 1 of the limit switch 38-FL. The capstan 37 is driven at a uniform speed by means of a jockey pulley 53 driven at its periphery by the shaft 52 of the motor 51, whilst the supply and take-up reels 32, 33, respectively, are driven by friction means permitting slip by the motors 64, 69, respectively. The tape may be wound forward at a faster rate than normal, as when locating a particular part of the recording, or rewound at slow speed, without removing the tape from its existing position, by operating the " Fast Forward " switch 73 or " Rewind switch 74, respectively. In the former case the Forward " switch 72 is released by the operation of switch 73 so that the pads 81 are released from pressure on the tape and the capstan 37 is uncoupled from the motor 51 by means of the lever 74-D. In the latter case the switch 72 is also released but the motor 51 remains coupled and produces a drag on the tape which is slowly rewound on to the spool 32 by the motor 64. A fast rewind may be accomplished by removing the tape from the path 31-F over capstan 37 and placing it along the path 31-R over the limit-switch member 39 which maintains a circuit through the motor 64 by means of the contacts 2 on the limit switch 39-RL. The limit switches 38, 39, which assure that the motor circuits are interrupted in the event of breakage of the tape or when all the tape has been wound on one of the spools, may be replaced by a single switch member 40-2 which is frictionally coupled to a drum 40. The switch member 40-2 operates switch 38-FLL or 39-RLL according to the direction of travel of the tape, the contacts of the switches 38-FLL and 39-RLL being identical to those of the switches 38-FL and 39-RL, respectively. In a slow forward or rewinding operation the tape is placed along the path 31-4, and in the path 31-5 for a fast forward or rewind operation. Another construction is described, Fig. 11 (not shown), in which only one motor is used, the spools being driven through magnetic clutches by the motor driving the capstan 37. Two other constructions are described, Figs. 6, 7, 8 (not shown), of modified arrangements for pressing the tape into contact with the transducer and erasing head, while a different layout of the spools and capstan is described with reference to Figs. 8 and 9 (not shown), in which lever arms are provided for releasing the tape from the capstan 37 during a fast reeling operation. In this arrangement and in a further one, Fig. 10 (not shown), it is not necessary to remove the tape to a different position for fast forward or rewinding. Figs. 5 and 6 (not shown) illustrate the mounting of the transducer and erasing head, including the guides for the tape. Fig. 12 (not shown), illustrates a method of temporarily stopping the tape and disengaging it from the driving capstan by the use of a manually applied brake to the take-up reel whereby tension of the tape over the capstan is released.